cve-2026-64070

MEDIUM CVSS 5.5 nvd
Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb) (which calls preempt_disable()) but only call the matching put_cpu_var() on the error path under the 'out:' label. Every successful read leaks one preempt_disable(): processor_bus_topology_show() processor_config_show() affinity_domain_via_virtual_processor_show() affinity_domain_via_domain_show() (affinity_domain_via_partition_show() was already correct.) On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and eventually return to userspace with preemption still disabled. The next user-mode page fault then hits faulthandler_disabled() == 1, gets forced to SIGSEGV, and the resulting coredump trips 'BUG: scheduling while atomic' in call_usermodehelper_exec -> wait_for_completion_state -> schedule: BUG: scheduling while atomic: <task>/<pid>/0x00000004 ... __schedule_bug+0x6c/0x90 __schedule+0x58c/0x13a0 schedule+0x48/0x1a0 schedule_timeout+0x104/0x170 wait_for_completion_state+0x16c/0x330 call_usermodehelper_exec+0x254/0x2d0 vfs_coredump+0x1050/0x2590 get_signal+0xb9c/0xc80 do_notify_resume+0xf8/0x470 Add an out_success label that calls put_cpu_var() before returning the byte count, mirroring affinity_domain_via_partition_show().

Timeline
Published
2026-07-19
Last Modified
2026-09-03
CVSS Details
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
Affected Products
  • linux linux_kernel
CVSS metrics
Version Base Severity Vector Exploitability Impact Source
3.1 5.5 MEDIUM CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H 1.8 3.6 nvd@nist.gov
CPE configurations
OR
CPE Version range Vulnerable
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.6, < 6.6.156 yes
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.7, < 6.12.108 yes
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.13, < 6.18.49 yes
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.19, < 7.0.11 yes
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* — yes
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* — yes
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* — yes
NVD metadata
NVD status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
Linked Vulnerabilities

No linked vulnerabilities found.

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  "datePublished": "2026-07-19T16:17:47.583",
  "dateUpdated": "2026-09-03T15:11:27.580",
  "description": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/hv-gpci: fix preempt count leak in sysfs show paths\n\nFour sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)\n(which calls preempt_disable()) but only call the matching put_cpu_var()\non the error path under the 'out:' label. Every successful read leaks\none preempt_disable():\n\n  processor_bus_topology_show()\n  processor_config_show()\n  affinity_domain_via_virtual_processor_show()\n  affinity_domain_via_domain_show()\n\n(affinity_domain_via_partition_show() was already correct.)\n\nOn a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and\neventually return to userspace with preemption still disabled. The\nnext user-mode page fault then hits faulthandler_disabled() == 1,\ngets forced to SIGSEGV, and the resulting coredump trips\n'BUG: scheduling while atomic' in call_usermodehelper_exec ->\nwait_for_completion_state -> schedule:\n\n  BUG: scheduling while atomic: <task>/<pid>/0x00000004\n  ...\n  __schedule_bug+0x6c/0x90\n  __schedule+0x58c/0x13a0\n  schedule+0x48/0x1a0\n  schedule_timeout+0x104/0x170\n  wait_for_completion_state+0x16c/0x330\n  call_usermodehelper_exec+0x254/0x2d0\n  vfs_coredump+0x1050/0x2590\n  get_signal+0xb9c/0xc80\n  do_notify_resume+0xf8/0x470\n\nAdd an out_success label that calls put_cpu_var() before returning\nthe byte count, mirroring affinity_domain_via_partition_show().",
  "id": "CVE-2026-64070",
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        "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/hv-gpci: fix preempt count leak in sysfs show paths\n\nFour sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)\n(which calls preempt_disable()) but only call the matching put_cpu_var()\non the error path under the 'out:' label. Every successful read leaks\none preempt_disable():\n\n  processor_bus_topology_show()\n  processor_config_show()\n  affinity_domain_via_virtual_processor_show()\n  affinity_domain_via_domain_show()\n\n(affinity_domain_via_partition_show() was already correct.)\n\nOn a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and\neventually return to userspace with preemption still disabled. The\nnext user-mode page fault then hits faulthandler_disabled() == 1,\ngets forced to SIGSEGV, and the resulting coredump trips\n'BUG: scheduling while atomic' in call_usermodehelper_exec ->\nwait_for_completion_state -> schedule:\n\n  BUG: scheduling while atomic: <task>/<pid>/0x00000004\n  ...\n  __schedule_bug+0x6c/0x90\n  __schedule+0x58c/0x13a0\n  schedule+0x48/0x1a0\n  schedule_timeout+0x104/0x170\n  wait_for_completion_state+0x16c/0x330\n  call_usermodehelper_exec+0x254/0x2d0\n  vfs_coredump+0x1050/0x2590\n  get_signal+0xb9c/0xc80\n  do_notify_resume+0xf8/0x470\n\nAdd an out_success label that calls put_cpu_var() before returning\nthe byte count, mirroring affinity_domain_via_partition_show()."
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  "title": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/hv-gpci: fix preempt count leak in sysfs..."
}
Enrichment data
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